Automatic fuel control system for an internal combustion engine



Aug. 17, 1955 K. DLUHOSCH ETAL 3,200,802

AUTOMATIC FUEL CONTROL SYSTEM FOR AN INTERNAL COMBUSTION ENGINE Eiled Feb. 6, 1965 lllln;

ll/A @aM w United States Patent 3,200,892 AUTOMATED FUEL CONTROL SYSTEM FOR AN INTERNAL COMBUSTION ENGINE Kurt Dluhosch and Gerd Ottcrbach, Schweinfurt (Main),

Germany, assignors to Fichtel & Sachs A.G., Schweinfurt (Main), Germany, a corporation of Germany Filed Feb. 6, 1963, Ser. No. 256,717 Claims priority, application Germany, Feb. 10, 1962, 35,996/ 62 11 Claims. (Cl. 123-97) This invention relates to the automatic control of the fuel supply of a fuel-operated engine, and more particularly to a system for automatically controlling the fuel supply of an internal combustion engine responsive to the rotary speed of the output shaft of the engine.

It is known to control the fuel supply of an internal combustion engine responsive to the rotary speed of an output shaft of the engine, the output shaft being the crankshaft of the engine if the same is of the piston type, or the output shaft of a speed-changing transmission connected to the crankshaft of the piston engine or to the drive shaft of a rotary engine, such as a turbine. The known control devices are only semi-automatic and require the intervention of an operator or of other external agents during starting.

An engine of the type described operates under three sets of basic conditions. The first set of conditions prevails during start-up, the second set during normal operation under load, and the third set of conditions during idling. Transition from the first to the second set of conditions requires a relatively large change in the setting of a fuel control element such as the throttle of a carburetor or the valve which controls the fuel input from a fuel injection system. A relatively small movement of the fuel control element is required for transition from the second to the third set of conditions.

It is conventional to connect a centrifugal speed governor to the engine output shaft for actuating movement of the fuel control element through a linkage attached to the weighted arms of the centrifugal governor. The radial movement of the weighted arms which determines the movement of the linkage is normally of about equal magnitude during transition from starting conditions to full-load conditions, and during transition from full-load to idling conditions. Since it is generally desirable to make the centrifugal governor as small as possible, it has been customary heretofore to control only the transition between the second and third sets of conditions in an automatic manner by means of a centrifugal governor, and to rely on intervention of the operator or of other external means for controlling the fuel supply during transition from the starting condition to full-load operation.

The primary object of the invention is the provision of a system in which the fuel supply to an engine is automatically controlled over the full range of operating conditions by a speed governor responsive to the speed of the engine.

A more specific object is the provision of such a system in which the fuel supply controls are linked to a speed governor by motion transmitting means having a variable transmission ratio which is changed automatically as the speed governor linkage moves.

With these and other objects in view, the invention in one of its aspects interposes motion transmitting means between the fuel control means of anengine and a member of the speed governor assembly which moves in a predetermined path responsive to the speed of the engine. The motion transmitting means include two levers which are pivotally connected to each other. One of the levers is connected to the fuel control means, the other to a "Ice fixedv pivot. Respective portions of the two levers are equipped with engaging means which sequentially engage the levers to the aforementioned member of the speed governor assembly in such a manner that the levers move jointly with the governor member while the same moves in its predetermined path.

The exact nature of this invention as well as other features and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawing in which:

FIG. 1 shows a preferred embodiment of the invention in fragmentary side-elevational view; and

FIG. 2 illustrates the device of FIG. 1 in partly sectional front elevation.

Referring now to the drawing in detail, there is seen the automatic control system for the fuel supply of a conventional piston engine. Only portions of the stationary engine frame 20 are seen in the drawing. The engine is equipped with a centrifugal speed governor mechanism coupled to the output shaft of the engine in the usual manner, and represented in the drawing by a linkage rod 10 which moves longitudinally when the weighted arms of the speed governor move radially with respect to their axis of rotation.

The fuel supply to the engine passes through a carburetor assembly in the usual manner, and is controlled by movement of a throttle in the air throat of the car buretor as is conventional. The carburetor assembly is represented in the drawing by an accelerator rod 11 which is a part of the linkage connected to the throttle of the carburetor in a manner conventional in itself and not illustrated since it is not relevant to this invention.

The movements of the speed governor are transmitted to the carburetor by means of two levers 2, 4. The twoarmed first lever 4 has one arm connected to the accelerator rod 11 by a ball joint 21. A projection 24 on the other arm abuttingly engages a plate 12 on the linkage rod 10 under the urging of a strong helical tension spring 5 fastened to the engine frame 20.

A pivot pin 1 is fixed in the engine frame 20, and pivotally supports one end of the one-armed second lever 2. In the position of the apparatus illustrated in fully drawn and broken lines in FIG. 1, a projection 22 on the other end of the lever 2 is spaced from the plate 12 in the direction in which the linkage rod 10 moves when the speed of the engine increases. The central portions of the levers 2, 4 are hingedly connected by a pivot pin 3 which is fixedly fastened to the lever 2.

A stud 7 is rotably mounted in a portion of the engine frame 25). The stud carries an integral fixed flange 17 on one axial end, and a threaded pin 18 on the other axial end. A movable flange 19 is loosely slipped over the pin 18, and held in position by two nuts 9. T ightening of the nuts 9 forces the two flanges against each other and against respective faces of the frame portion so as to fasten the stud to the frame. A stop pin S eccentrically mounted on the flange 17 projects into the path of pivotal movement of the lever 2 about the axis of the fixed pivot pin 1. The spring 5 urges the lever 2 toward a normal position in which the lever 2 abuts against the pin 8. This normal position may be adjusted by loosening the nuts 9, turning the stud 7, and again tightening the nuts 9.

The accelerator rod 11 is biased by a return spring 6 toward the position shown in FIG. 1 in fully drawn lines. The return spring is mounted between the engine frame 29 and a portion of the lever 4 adjacent the ball joint 21. The force of the return spring 6 is selected so as not to interfere with movements actuated by the spring 5. The springs 5, 6 have been omitted from FIG. 2 for the sake of clarity.

each phase of engine operation.

The afore-described apparatus as follows:

The fully drawn and broken lines show the apparatus of FIG. 1 in the position assumed when the engine stands still. The abutment face of the plate 12 is in a position S, and the center of the ball joint 21 between the accelerator rod 11 and the first lever 4 is in a position S in which the carburetor is set by the accelerator rod l t for supplying the amount of fuel required for engine start-up. The starting position of the lever is determined by the abutment of the lever 2 against the stop pin 8. Rotary adjustment of the stud 7 thus varies the normal starting position of the accelerator rod 11, and thereby the amount of fuel initially supplied during start-up.

When the engine is started, the rod 10 moves longitudinally, and the lever 4 is thereby pivoted about the axis of the pin 3 in a clockwise direction, as viewed in FIG. 1, against the restraint of the Springs 5, 6. The accelerator rod 11 is thereby shifted in the general direction of its elongation to reduce the throttle opening of the carburetor and to reduce the amount of fuel supplied to the engine.

The lever 2 remains in its original position until the abutmentface of the plate 12 reaches the position V, and the ball joint 21 reaches the corresponding position V. In the position V, the plate 12 abuts against the projection 22 on the lever 2. This position corresponds to operation of the engine at full load.

If the engine load is reduced, the speed of the output shaft of the engine and the speed of the speed governor are further increased. The plate 12 is shifted toward the position L, and the levers 2, 4 are jointly pivoted about the fixed axis of the pin 1 while being held against the plate 12 by the combined forces of the springs 5 and 6 toward a position ofthe levers indicated by chain-dotted outlines. The ball joint 21 moves toward the position L. The fuel supply to the engine is throttled to the amount required for idling when the positions L, L are reached.

During movement of the lever 4 from the starting positions S, S to the full-load positions V, V the plate 12 moves about the same distance as during movement of the lever 4 from the full-load positions V, V to the idling positions L, L. Yet, the accelerator rod 11 moves over a substantially greater distance from start-up to fullload, than from full-load to idling. The difference is due to the shifting of the pivoting axis of the lever 4 from the pivot pin 3 to the pivot pin 1 which is interposed between the ball joint 21 and the pin 3. When the engine is stopped, the control system reverts to its original position determined by abutment of the lever 2 against the stop pin 8.

The apparatus of the invention thus automatically sets the carburetor to the position of adequate fuel supply for starting when the engine is stopped. When the engine is started, the transition from starting conditions to fullload operation is automatically controlled by the centrifugal speed governor. The proper mechanical advantage of the lever system is established automatically for The automatic control of the fuel supply to the engine is achieved with a single centrifugal governor which may be of relatively small dimensions.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention, and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

What is claimed is:

1. In a system for automatic control of the fuel supply of a fuel-operated engine, in combination:

(a) control means movable for controlling the fuel supply of an engine;

(b) speed governor means including a governor member movable in a predetermined path responsive to the speed of said engine; and

(c) motion transmitting means interposed between said control means'and said governor means, said motion transmitting means including:

(1) a first lever member having three spaced portions, a first one of said portions being secured to said control means;

(2) a second lever member having three spaced portions;

(3) first pivot means engaging a first portion of said second lever member for pivotal movement of said second lever member about a fixed axis;

(4) second pivot means pivotally connecting respective second portions of said lever members; and

(5) engaging means for sequentially engaging the third portions of said lever member with said governor member when said governor member moves in said predetermined path, said engaging means including holding means for holding the engaged third portions in engagement with said governor member for joint movement therewith.

2. In a system as set forth in claim 1, said first and second portions of one of said lever members being spaced in a common direction from said third portion of said one lever member.

3. In a system as set forth in claim 2, said one lever member being said second lever member.

4; In a system as set forth in claim 1, said engaging means including. abutting means on each of said third portions of said lever'members for sequential abutting engagement with said governor member.

'5. In a system as set forth in claim 4, yieldably resilient means urging said third portion-s to move toward a normalposition in which said third portions are spaced from each other along said predetermined path.

6. In a system as set forth in claim 5, stop means engageable with one of said lever members for stopping movement thereof under the urging of said resilient means in said normal position.

' 7.'In a system as set forth in claim 6, means for varying the position of said stop means and for thereby varying said normal position.

8. In a system as set forth in claim 1, said fixed axis being interposed between said second portion of said first lever and said first portion thereof when said first lever is in said normal position thereof.

9. In a system as set forth in claim 1, said holding means including yieldably resilient means biasing the third portion of one of said lever members toward said governor member.

10. In a system as set forth in claim 9, said one lever member being said second lever member.

11. A motiontransmitting linkage between two movable elements'comprising, in combination:

(a) a support;

(b) afirst lever member havingthree spaced portions;

(0) means for securing a first one of said portions to one of said elements;

(d) a second lever member having three spaced portrons;

(e) first pivot means mounted on said support and engaging a first portion of said second lever memberfor pivotal. movement of the second and third portions thereof about an axis fixed with respect to said support;

(f) second pivot means pivotally connecting a second portion of said first lever member to said second portion of said second lever member; and

(g) engaging means for sequentially engaging the third portions of said lever members with the other one of said elements when said other element, moves,

5 6 said engaging means including 'eidably resilient 2,598,960 6/52- Adler 123108 means for biasing the third portion of one of said 2,817,323 12/57 Nallinger 123-198 lever members toward a position of engagement 2,836,162 5/58 Dressler 123-139 with said other element. 2,891,526 6/59 Shephard et a1. 123-98 5 FOREIGN PATENTS References Cited by the Examiner UNITED STATES PATENTS 1,257,918 2/18 Noack 73-531 FRED E. ENGELTHALER, Primary Examiner. 2,436,897 3/48 Nutt 74516 704,801 3/54 Great Britain. 

1. IN A SYSTEM FOR AUTOMATIC CONTROL OF THE FUEL SUPPLY OF A FUEL-OPERATED ENGINE, IN COMBINATION: (A) CONTROL MEANS MOVABLE FOR CONTROLLING THE FUEL SUPPLY OF AN ENGINE; (B) SPEED GOVERNOR MEANS INCLUDING A GOVERNOR MEMBER MOVABLE IN A PREDETERMINED PATH RESPONSIVE TO THE SPEED OF SAID ENGINE; AND (C) MOTION TRANSMITTING MEANS INTERPOSED BETWEEN SAID CONTROL MEANS AND SAID GOVERNOR MEANS, SAID MOTION TRANSMITTING MEANS INCLUDING: (1) A FIRST LEVER MEMBER HAVING THREE SPACED PORTIONS, A FIRST ONE OF SAID PORTIONS BEING SECURED TO SAID CONTROL MEANS; (2) A SECOND LEVER MEMBER HAVING THREE SPACED PORTIONS; (3) FIRST PIVOT MEANS ENGAGING A FIRST PORTION OF SAID SECOND LEVER MEMBER FOR PIVOTAL MOVEMENT OF SAID SECOND LEVER MEMBER ABOUT A FIXED AXIS; 